Di Maria may be attainable. Apparently Real Madrid wants to buy James Rodriguez, and would need to sell Di Maria in order to fund it.
Honestly more than anything else we need a trequartista. I would honestly buy Cassano at this point. He isn't ideal, but would be affordable and seems to have matured. I can't remember which player it was at Italy camp it was, but they called him the most likeable player there. It would allow us to play a 3-4-1-2 as an alternative to a 3-1-4-2. He also could allow us to play a 3-4-2-1. Like him or not, he is very versatile and would give Conte more options. He is cheap, and is likely gone from Parma. He also has the southern Italian connection with Conte (Bari & Lecce). Even though, he fell flat with the rest of the Azzurri this WC, he was incredibly consistent in Serie A. Also ask Tottenham fans, he single handedly beat them with Inter in the return leg of the Europa two years ago.
As for Di Maria, I'd look to sell Asamoah to fund him. Di Maria is so incredibly versatile. He is perfect in a 4-3-3 as the RWer, and perfect in a 3-5-2 as the Left Wingback. He also can play central mid, not like we'd need it.